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Your discount rate is generally the rate you can borrow at, so it differs for everyone.

To see why, consider a really simple case: you can buy a contract to receive C cash at some time T in the future. Call X how much you'd pay today to enter that contract. You can borrow X today and agree to repay it using the payout from your contract. If you can borrow at a fixed, continuously compounded rate R, then the amount you repay is X exp(RT). So your breakeven (or "fair") price would have X exp(RT) = C, i.e. X = C exp(-RT). NB, the rate you use to discount a future value to know its present value to you is R, which is _your_ rate to borrow that much money for that length of time.

There are various models that aim to recover R from other values, but ultimately it's determined by market activity. Lenders either will or will not loan you X for T time at a rate of R.

What kinds of things might impact their willingness? Definitely their perception of present and future inflation rates, but also their ability to loan at a higher rate to someone else with a similar risk profile (i.e. the "rates market" as a whole) and also specifics of your own credit risk to them. If they think you might default on the loan, they'll charge you more for that added risk.